Follow us on Twitter
twitter icon@FreshPatents

Browse patents:
Next
Prev

High yield yellow fever virus strain with increased propagation in cells / Xcellerex, Inc.




Title: High yield yellow fever virus strain with increased propagation in cells.
Abstract: The invention provides a an inactive, non-replicating vaccine comprising whole virion, chemically inactivated Yellow Fever virus which is inactivated using a method that ensures preservation of critical, neutralizing epitopes. The Yellow Fever virus has been adapted to propagate in cells to higher yields than the unadapted virus. The invention also provides methods for preventing Yellow Fever viral infection. ...


Browse recent Xcellerex, Inc. patents


USPTO Applicaton #: #20110287519
Inventors: Cynthia K. Lee, Thomas P. Monath, Patrick M. Guertin, Edward G. Hayman


The Patent Description & Claims data below is from USPTO Patent Application 20110287519, High yield yellow fever virus strain with increased propagation in cells.

RELATED APPLICATION

This application is a continuation-in-part of copending International Application No. PCT/US2010/043010, filed on Jul. 23, 2010, which claims the benefit of priority to U.S. Provisional Application No. 61/230,483, filed on Jul. 31, 2009. The entire teachings of the above applications are incorporated herein by reference.

BACKGROUND

- Top of Page


OF THE INVENTION

The Yellow Fever virus is endemic, that is, continuously present with low levels of infection in some tropical areas of Africa and the Americas, where it regularly amplifies into epidemics. Other parts of the world, including coastal regions of South America, the Caribbean islands, and Central and North America, are infested with the mosquito vector capable of transmitting the virus and are therefore considered at risk for yellow fever epidemics (World Health Organization Fact Sheet No. 100, revised December, 2001).

For example, in Africa alone, thirty-three countries with a combined population of 508 million, are at risk (Id.). Each year, the World Health Organization (WHO) estimates there are 200,000 cases of yellow fever, with 30,000 deaths (Id.). Travel to these tropical regions also is believed to result in a small number of imported cases in countries generally free of yellow fever. Although yellow fever cases have not been reported in Asia, “this region is at risk because the appropriate primates and mosquitoes are present” (Id.).

The Yellow Fever (YF) virus is in the genus Flavivirus, in the family Flaviviridae. In the so-called “jungle” or “sylvan cycle”, the YF virus is enzootic, maintained and transmitted by canopy breeding mosquitoes to monkeys in the rainforests. The “urban cycle” begins when humans become infected by entering the rainforests and are bitten by YF-infected mosquitoes. The “urban cycle” continues with peridomestic transmission from humans to mosquitoes and thence to other humans, and can result in yellow fever epidemics in villages and cities. Illness ranges in severity from a self-limited febrile illness to severe hepatitis and fatal hemorrhagic disease.

Unvaccinated humans, including both native people and travelers to YF endemic areas are at significant risk of YF infection when occupational and other activities bring them in contact with infected mosquitoes in the sylvan cycle or the urban cycle.

Patients with yellow fever may be viremic, i.e., have virus in their blood, for 3 to 6 days during the early phase of illness. This phase may be followed by a short period of symptom remission.

The toxic phase develops as the fever returns, with clinical symptoms including, for example, high fever and nausea, hemorrhagic symptoms, including hematemesis (black vomit), epistaxis (nose bleed), gum bleeding, and petechial and purpuric hemorrhages (bruising). Deepening jaundice and proteinuria frequently occur in severe cases.

In the late stages of disease, patients can develop hypotension, shock, metabolic acidosis, acute tubular necrosis, myocardial dysfunction, and cardiac arrhythmia. Confusion, seizures, and coma can also occur, as well as complications such as secondary bacterial infections and kidney failure.

There is no specific treatment for yellow fever. Steps to prevent yellow fever include use of insect repellent, protective clothing, and vaccination with the available, but risky attenuated vaccine.

Live, attenuated vaccines produced from the 17D substrain, are available, but adverse events associated with the attenuated vaccine can lead to a severe infection with the live 17D virus, and serious and fatal adverse neurotropic and viscerotropic events, the latter resembling the severe infection by the wild-type YF virus. Thus there is a need for a safer, inactivated, non-replicating vaccine that will elicit a neutralizing antibody response while eliminating the potential for neurotropic and viscerotropic adverse events.

Thus, there is an on-going need for an effective, inactivated, “killed” or non-replicating vaccine in order to avoid the potential for neurotropic and viscerotropic adverse events associated with the currently available attenuated YF 17D vaccine. Further, there is a need for an improved vaccine produced in Vero cells without animal-derived proteins, a vaccine that can be safely used for persons for whom the live vaccine is contraindicated or for whom warnings appear on the label. Such individuals include immuno-suppressed persons, persons with thymic disease, egg-allergic, young infants, and the elderly.

A problem with any potential inactivated virus is that it may need to be delivered at a higher titer than the existing live attenuated vaccines, because the latter can expand antigenic mass during cycles of replication in the host whereas an inactivated vaccine contains a fixed dose of antigen. Therefore, in order to develop a sufficiently potent inactivated vaccine, it is desirable to modify the YF virus in order to produce a high yield of virus in the conditioned medium (also called supernatant fluid) of a cell culture. It is highly desirable to use the attenuated 17D vaccine strain for vaccine manufacturing, since the 17D strain can be manipulated at a lower level of biocontainment than the wild-type virulent YF virus. However, the attenuated 17D vaccine strain yields in cell culture are inherently lower than yields of wild-type virus. For these reasons, modifications of the 17D vaccine strain to achieve higher yields in cell culture used for vaccine production would be useful.

BRIEF

SUMMARY

- Top of Page


OF THE INVENTION

The invention provides a vaccine comprising a strain or strains of Yellow Fever virus which have been adapted to propagate in Vero cells to higher yields than an unadapted virus. “Unadapted virus” is defined to mean that Yellow Fever virus vaccine known as 17D. Sequence analysis of examples of such strains demonstrates that an adapted virus possessing a mutation in the envelope (E) protein resulting in a lysine to arginine substitution in amino acid residue 160 has improved properties. The invention also provides for vaccines comprising a Yellow Fever virus containing one or more mutations in the E protein, that result in increased propagation in Vero cells and in higher yields when using serum free culture medium than the unadapted virus.

Additional examples of adapted Yellow Fever virus strains which propagate in Vero cells to higher yields than unadapted virus have been identified. These include modified Yellow Fever virus strains wherein the nucleic acid molecules of said modified Yellow Fever virus strains comprise at least one amino acid mutation selected from: an amino acid mutation in the NS1 protein, an amino acid mutation in the NS2A protein, and an amino acid mutation in the NS4B protein, optionally wherein said at least one amino acid mutation is in further combination with an amino acid mutation in the envelope protein. Preferred embodiments include 1) a strain having three mutations: a) a lysine to arginine substitution in amino acid residue 160 (lys160arg) in the E protein, b) a threonine to isoleucine substitution in amino acid residue 317 (thr317ile) in the non-structural protein 1 (NS1), and c) a phenylalanine to leucine substitution in amino acid residue 170 (phe170leu) in the non-structural protein 2A (NS2A); and 2) a strain with a mutation in the non-structural protein 4B (NS4B), resulting in an isoleucine to methionine substitution at amino acid residue 113 (ile113met).

The invention provides for vaccines comprising a Yellow Fever virus containing one or more mutations selected from: a mutation in the NS1 protein optionally combined with a mutation in the E protein; a mutation in the NS2A protein optionally combined with a mutation in the E protein; and a mutation in the NS4B protein optionally combined with a mutation in the E protein that result in increased propagation in Vero cells and in higher yields than the unadapted virus.

The Yellow Fever virus is the prototype species in the genus Flavivirus, in the family Flaviviridae. Structural and functional studies of the E protein of tick-borne encephalitis (TBE) virus, a fast-growing, virulent member of the flavivirus genus, indicate that Domains I and II in the E protein of TBE participate in an acidic pH-dependent conformational change that facilitates flavivirus membrane fusion with the host and subsequent infectivity. The junction of Domains I and II function as a ‘molecular hinge’ resulting in a major rearrangement of these domains from of the normal dimeric structure of the E protein at acid pH into a homotrimeric state. [Rey F A et al. The envelope glycoprotein from tick-borne encephalitis virus at 2 Å resolution. Nature 375: 291-298 (1995); Heinz F X et al. Structural changes and functional control of the tick-borne encephalitis virus glycoprotein E by the heterodimeric association with protein prM. Virology 198: 109-117 (1994); Mandl C W et al. Antigenic structure of the flavivirus envelope protein E at the molecular level, using tick-borne encephalitis virus as a model. Journal of Virology 63(2): 564-571 (1989); Harrison S C. Viral membrane fusion. Nature structural and molecular biology 15(7): 690-698 (2008); Stiasny K et al. Molecular mechanisms of flavivirus membrane fusion. Amino acids DOI 10.1007/s00726-009-0370-4, published on line 1 Nov. 2009.]

Lys 160 in the E protein of Yellow Fever virus is located in the molecular hinge region between Domains I and II. Mutations in this region could alter the acid-dependent conformational change in region Domain I of the E protein required for fusion and virus internalization into the cell cytoplasm. Without being bound by theory, higher yields seen with the lysine to arginine change at amino acid 160 in Domain I of the E protein of the adapted Yellow Fever virus strain may be due to an increased affinity for protons that arginine provides as compared with lysine, that results in enhanced membrane fusion with the host and more efficient infectivity. In regard to the invention, it is important to note that the side chains of lysine and arginine have pKa values of 10.53 and 12.48, respectively, indicating a one hundred fold greater affinity for protons in arginine than in lysine. The increased affinity for protons that the side chain of arginine shows relative to lysine\'s side chain may enhance the rate and efficiency of E protein conformational change at the molecular hinge, membrane fusion, and flavivirus infectivity, resulting in higher yields of virus in the adapted virus strain.

Other members within the genus Flavivirus include West Nile, dengue, and Japanese encephalitis viruses. The non-structural proteins found in West Nile Virus are known to be directly or indirectly involved in viral RNA synthesis. Amino acid substitutions in the non-structural proteins of these viruses have been shown to affect the yields of mutant viruses grown in Vero cells. For example, a proline to leucine substitution at amino acid 250 in the NS1 protein of the flavivirus Kunjin, a West Nile Virus subtype, grows at 100-fold lower titers than wild-type virus. Similarly, mutation of the C-terminal sites in the NS2A protein of yellow fever virus was shown to be lethal for virus replication. Brinton Mass. The molecular biology of west nile virus: a new invader of the western hemisphere. Annual Review of Microbiology 56: 371-402 (2002).

In a first aspect, the invention provides a modified Yellow Fever virus strain that results in increased propagation in Vero cells and a higher yield in the conditioned medium of a cell culture relative to the unadapted virus comprising at least one mutation relative to the unadapted virus selected from: a mutation in the E protein, a mutation in the NS1 protein, a mutation in the NS2A protein, and a mutation in the NS4B protein, optionally wherein said at least one mutation in the NS1 protein, the NS2A protein, or the NS4B protein is in further combination with a mutation of the E protein.

Replacement of basic amino acids that are located within 20 amino acids, or within 10 Angstroms, of lysine 160 in the E protein of the Yellow Fever virus (including lysine 160 itself), with amino acids having higher side chain pKa values than the replaced basic amino acids, can result in strains of Yellow Fever virus that produce higher yields of virus than an unadapted Yellow Fever virus. The invention thus provides for Yellow Fever viruses, and vaccines containing them, comprising a modified nucleic acid molecule encoding an E protein, the virus being capable of propagating in Vero cells to higher yields than the unadapted virus. Preferred embodiments include viruses comprising a modified E protein with an increased pKa within 20 amino acids, or within 10 Angstroms, of lysine 160 in the E protein.

In a third aspect, the invention provides a nucleic acid molecule comprising a sequence encoding a modified envelope protein of the Yellow Fever virus, wherein said nucleic acid molecule comprises a nucleotide mutation in the codon for the amino acid at position 160 of the envelope protein. In an embodiment of this aspect, the invention provides a nucleic acid molecule comprising a sequence encoding at least one modified nucleic acid relative to the nucleic acid of the unadapted virus, wherein said at least one modified nucleic acid is selected from: a modified nucleic acid of the NS1 protein, a modified nucleic acid of the NS2A protein and a modified nucleic acid of the NSB4 protein, optionally wherein said at least one modified nucleic acid is in further combination with a modified nucleic acid of the envelope protein of the Yellow Fever virus, wherein said optional modified nucleic acid of the envelope protein comprises a nucleotide mutation in the codon for the amino acid at position 160 of the envelope protein. In a further embodiment of this aspect, the nucleotide mutation in the codon for the amino acid at position 160 of the envelope protein results in a change from AAG to AGG, AGA, CGC, CGA, CGG or CGU. Additionally, the invention provides for vectors, constructs, modified Yellow Fever virus strains, and cells comprising or containing such a nucleic acid molecule or a protein encoded thereby.

In a fourth aspect, the invention provides a modified Yellow Fever virus strain, wherein the nucleic acid molecule of said strain comprises a sequence encoding an envelope protein of the Yellow Fever virus, wherein said envelope protein comprises an amino acid mutation at position 160 of the envelope protein. In an embodiment of this aspect, the invention provides a modified Yellow Fever virus strain, wherein the nucleic acid molecule of said strain comprises a sequence encoding an envelope protein of the Yellow Fever virus, wherein said envelope protein optionally comprises an amino acid mutation at position 160 of the envelope protein.

In a fifth aspect, the invention provides a nucleic acid molecule comprising a sequence encoding an envelope protein of the Yellow Fever virus, wherein said envelope protein comprises an amino acid mutation at position 160 of the envelope protein. In an embodiment of this aspect, the invention optionally provides a nucleic acid molecule comprising a sequence encoding an envelope protein of the Yellow Fever virus, wherein said envelope protein comprises an amino acid mutation at position 160 of the envelope protein. Additionally, the invention provides for vectors, constructs, modified Yellow Fever virus strains, and cells comprising or containing such nucleic acid molecules or proteins encoded thereby. The nucleic acid molecules preferably comprise a sequence encoding a modified envelope protein of the Yellow Fever virus, wherein said nucleic acid molecule encodes the protein sequence in SEQ ID NO. 4, 6, or 7.

In a sixth aspect, the invention provides a method for enhancing the propagation of Yellow Fever virus in cells. In an embodiment of this aspect, the method comprises mutating a nucleic acid molecule comprising a sequence encoding the envelope protein of the Yellow Fever virus, wherein the mutation comprises a nucleotide mutation in the codon for the amino acid at position 160 of the envelope protein. In another embodiment of this aspect, the method optionally comprises mutating a nucleic acid molecule comprising a sequence encoding the envelope protein of the Yellow Fever virus, wherein the mutation comprises a nucleotide mutation in the codon for the amino acid at position 160 of the envelope protein. In a further embodiment, the method comprises mutating a nucleic acid molecule comprising a sequence encoding the envelope protein of the Yellow Fever virus, wherein said mutation comprises an amino acid mutation at position 160 of the envelope protein. In a final embodiment, the method optionally comprises mutating a nucleic acid molecule comprising a sequence encoding the envelope protein of the Yellow Fever virus, wherein said mutation comprises an amino acid mutation at position 160 of the envelope protein. The word “mutating” is intended to mean selecting for a mutation, or introducing a mutation. The relevant mutant viruses can be obtained by a method of selection and evolutionary pressure during passages in a specific host cell line (such as Vero cells) or by site-directed mutagenesis using infectious clone technology well known in the art. However, the former method is preferred because it identifies mutated viruses by virtue of the desired phenotypic characteristic (increased yields in Vero cell cultures).

In a seventh aspect, the invention provides a modified Yellow Fever virus strain, wherein the nucleic acid molecule of said strain comprises a nucleotide mutation in the codon for amino acids flanking the E160 codon selected from position 134, 137, 144, 148, 157, 160, 175, or 177 of the envelope protein of Yellow Fever virus. In an embodiment of this aspect, the invention provides a modified Yellow Fever virus strain, wherein the nucleic acid molecule of said strain optionally comprises a nucleotide mutation in the codon for amino acids flanking the E160 codon selected from position 134, 137, 144, 148, 157, 160, 175, or 177 of the envelope protein of Yellow Fever virus. In another embodiment of this aspect, the mutated codon within 20 amino acids flanking the E160 mutation results in an amino acid mutation in the envelope protein at that position, wherein the pKa value of the side chain of the mutated amino acid is higher than the pKa value of the side chain of the original amino acid at that position.

In an eighth aspect, the invention provides for Yellow Fever viruses, and vaccines containing them, comprising a modified nucleic acid molecule encoding an NS1 protein, the virus being capable of propagating in Vero cells to higher yields than the unadapted virus. Preferred embodiments include viruses comprising a modified NS1 protein and a modified E protein. A more preferred embodiment includes viruses comprising a modified NS1 protein and a modified E protein with an increased pKa within 20 amino acids, or within 10 Angstroms, of lysine 160 in the E protein.

In a ninth aspect, the invention provides for Yellow Fever viruses, and vaccines containing them, comprising a modified nucleic acid molecule encoding an NS2A protein, the virus being capable of propagating in Vero cells to higher yields than the unadapted virus. Preferred embodiments include viruses comprising a modified NS2A protein and a modified E protein. A more preferred embodiment includes viruses comprising a modified NS2A protein and a modified E protein with an increased pKa within 20 amino acids, or within 10 Angstroms, of lysine 160 in the E protein.

In a tenth aspect, the invention provides for Yellow Fever viruses, and vaccines containing them, comprising a modified nucleic acid molecule encoding an NS1 protein and an NS2A protein, the virus being capable of propagating in Vero cells to higher yields than the unadapted virus. Preferred embodiments include viruses comprising a modified NS1 protein, a modified NS2 protein, and a modified E protein. A more preferred embodiment includes viruses comprising a modified NS1 protein, a modified NS2 protein, and a modified E protein with an increased pKa within 20 amino acids, or within 10 Angstroms, of lysine 160 in the E protein.

In an eleventh aspect, the invention provides for Yellow Fever viruses, and vaccines containing them, comprising a modified nucleic acid molecule encoding an NS4B protein, the virus being capable of propagating in Vero cells to higher yields than the unadapted virus.

In a twelfth aspect, the invention provides a nucleic acid molecule comprising a sequence encoding a modified non-structural protein 1 of the Yellow Fever virus, wherein said nucleic acid molecule comprises a nucleotide mutation in the codon for the amino acid at position 317 of the non-structural protein 1. In an embodiment of this aspect, the nucleotide mutation in the codon for the amino acid at position 317 of the non-structural protein 1 results in a change from ACA to AUA. Additionally, the invention provides for vectors, constructs, modified Yellow Fever virus strains, and cells comprising or containing such a nucleic acid molecule or a protein encoded thereby.

In a thirteenth aspect, the invention provides a nucleic acid molecule comprising a sequence encoding a modified non-structural protein 2A of the Yellow Fever virus, wherein said nucleic acid molecule comprises a nucleotide mutation in the codon for the amino acid at position 170 of the non-structural protein 2A. In an embodiment of this aspect, the nucleotide mutation in the codon for the amino acid at position 170 of the non-structural protein 2A results in a change from UUU to CUU. Additionally, the invention provides for vectors, constructs, modified Yellow Fever virus strains, and cells comprising or containing such a nucleic acid molecule or a protein encoded thereby.

In a fourteenth aspect, the invention provides a nucleic acid molecule comprising a sequence encoding a modified non-structural protein 4B of the Yellow Fever virus, wherein said nucleic acid molecule comprises a nucleotide mutation in the codon for the amino acid at position 113 of the non-structural protein 4B. In an embodiment of this aspect, the nucleotide mutation in the codon for the amino acid at position 113 of the non-structural protein 4B results in a change from AUA to AUG. Additionally, the invention provides for vectors, constructs, modified Yellow Fever virus strains, and cells comprising or containing such a nucleic acid molecule or a protein encoded thereby.

In a fifteenth aspect, the invention provides a modified Yellow Fever virus strain, wherein the nucleic acid molecule of said strain comprises a sequence encoding proteins of the Yellow Fever virus, wherein said proteins comprise an amino acid mutation at position 160 of the envelope protein, at position 317 of the NS1 protein, at position 170 of the NS2A protein, or at position 113 of the NS4B protein.




← Previous       Next →
Advertise on FreshPatents.com - Rates & Info


You can also Monitor Keywords and Search for tracking patents relating to this High yield yellow fever virus strain with increased propagation in cells patent application.

###


Browse recent Xcellerex, Inc. patents

Keyword Monitor How KEYWORD MONITOR works... a FREE service from FreshPatents
1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored.
3. Each week you receive an email with patent applications related to your keywords.  
Start now! - Receive info on patent apps like High yield yellow fever virus strain with increased propagation in cells or other areas of interest.
###


Previous Patent Application:
Polypeptide purification
Next Patent Application:
Salmonella marker vaccine
Industry Class:
Chemistry: molecular biology and microbiology
Thank you for viewing the High yield yellow fever virus strain with increased propagation in cells patent info.
- - -

Results in 0.10787 seconds


Other interesting Freshpatents.com categories:
Computers:  Graphics I/O Processors Dyn. Storage Static Storage Printers

###

Data source: patent applications published in the public domain by the United States Patent and Trademark Office (USPTO). Information published here is for research/educational purposes only. FreshPatents is not affiliated with the USPTO, assignee companies, inventors, law firms or other assignees. Patent applications, documents and images may contain trademarks of the respective companies/authors. FreshPatents is not responsible for the accuracy, validity or otherwise contents of these public document patent application filings. When possible a complete PDF is provided, however, in some cases the presented document/images is an abstract or sampling of the full patent application for display purposes. FreshPatents.com Terms/Support
-g2-0.1808

66.232.115.224
Browse patents:
Next
Prev

stats Patent Info
Application #
US 20110287519 A1
Publish Date
11/24/2011
Document #
File Date
12/31/1969
USPTO Class
Other USPTO Classes
International Class
/
Drawings
0


Strain

Follow us on Twitter
twitter icon@FreshPatents

Xcellerex, Inc.


Browse recent Xcellerex, Inc. patents



Chemistry: Molecular Biology And Microbiology   Virus Or Bacteriophage, Except For Viral Vector Or Bacteriophage Vector; Composition Thereof; Preparation Or Purification Thereof; Production Of Viral Subunits; Media For Propagating  

Browse patents:
Next
Prev
20111124|20110287519|high yield yellow fever virus strain with increased propagation in cells|The invention provides a an inactive, non-replicating vaccine comprising whole virion, chemically inactivated Yellow Fever virus which is inactivated using a method that ensures preservation of critical, neutralizing epitopes. The Yellow Fever virus has been adapted to propagate in cells to higher yields than the unadapted virus. The invention also |Xcellerex-Inc
';